The Clinical Transplant Center Core will be comprised of 10 major academic transplant centers in the United States doing approximately 1360 adult kidney transplants per year in total. Its activities will be integrated with the three Scientific Projects through the Clinical Database, the Program Project website, yearly scientific meetings and active interim interactions between the 10 Clinical Investigators and the Principal Investigators. Our focused objectives for this Core are to provide the Projects with the requisite patient materials and correlating clinical data to test the hypotheses that: 1) gene expression and proteomic signatures in PBL and kidney transplant biopsies can be identified that correlate with biopsy-proven acute rejection and chronic allograft nephropathy, 2) gene and protein expression profiles will provide insights into the molecular pathways involved in both the host immune response and the donor organ's response to transplantation, 3) the adequacy of immunosuppression as defined by the absence of rejection-related gene and protein expression can be determined at any given time by gene and protein expression profiles, and 4) targeted SNP genotyping and candidate gene sequence studies will identify connections between the genetics of the donor and the recipients that correlate with transplant events and outcomes as well as with gene and protein expression signatures. Arching over all these hypotheses, we propose to examine the possibility that race (Caucasian, African American and Hispanic) and/or sex will genetically influence at least a subset of genes and proteins expressed post transplant and correlate with clinical outcomes. A critical point is that the correct clinical designations of the patient subgroups and successful completion of enrollment and specimen acquisitions, the two primary tasks for this Core, will determine the potential of success for all the scientists in the entire Program Project.